Federal government information is still making its way online. Recent reports are often available online, but historical materials are slowly being digitized by agencies, libraries, and corporate vendors. The majority of historic government information is available in print at this time.
Tracking down older government information can be challenging (but worthwhile). Items from 1976-present should be in the library catalog, but items prior to 1976 are not necessarily in the catalog. The library is working on getting records for all of its government documents in the catalog, but it will take time to reflect 200 years worth of material in the catalog. If there isn't a record for the item you want in the catalog, the library may still own it; remember the 1976-present limitation. Try WorldCat, the digital Serial Set, or some of the print indexes to track down a call number.
You can always ask the Government Documents librarian for help in finding a government report. This is why we're here.